1. Field of the Invention
The apparatus and methods described herein are useful for separating fluid mixtures. In one embodiment, the apparatus and method can be used to separate a fluid stream comprising water and alcohol into at least one stream comprising primarily alcohol and one stream comprising primarily water. The separation is accomplished through the use of one or more vacuum distillation steps.
2. Description of the Prior Art
Water and alcohol mixtures form hydrogen bonds in the liquid and on the surface. The surface bonding force is surface tension and in normal distillation processes the escaping alcohol vapors and water vapors need to have enough energy to overcome the surface tension forces (including the chamber pressure). The vapor force needed to overcome the surface tension force is also referred to as vapor pressure. Vapor can escape the liquid when vapor pressure inside the liquid is greater than the surface tension forces. As one would expect, increasing the temperature of a liquid increase the liquids vapor pressure. Boiling begins when the vapor pressure exceeds the surface tension forces.
In standard distillation strippers, the trays used to separate the alcohol from the beer are at different temperatures and concentrations of alcohol. The beer in the tray has a depth and a flat surface. The flat surface indicates the surface tension is fixed and constant. The deeper the liquid in the tray the higher the vapor pressure has to be to form a bubble, or there needs to be movement of the fluid in the tray to place an alcohol molecule nearer the surface, reducing the required vapor pressure. The vaporizing process on each tray is in equilibrium and the standard alcohol water vapor-liquid-equilibrium (V-L-E) curve describes the process well. In order to break the alcohol-water azeotrope and recover a highly enriched alcohol distillate, the distillation environment must be changed so as to cause the beer not to follow V-L-E curve behavior.